<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <link rel="stylesheet" href="css.css"><!-- 外部样式的引入方式 -->
    <style> /* 内部样式 */
        div {
            width:100px;
            height: 100px;
            background-color: crimson;
        }
    </style>
    
</head>

<body>
    <div style="height: 200px;font-size: 20px;">这是一个div</div>
</body>

</html>